Дисертації з теми "Equatorial waves"
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King, B. A. "Loquency waves in equatorial oceans." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373656.
Повний текст джерелаLi, Xiaoqing. "Equatorial waves in planetary atmospheres." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335062.
Повний текст джерелаProehl, Jeffrey A. "Equatorial wave-mean flow interaction : the long Rossby waves /." Thesis, Connect to this title online; UW restricted, 1988. http://hdl.handle.net/1773/10960.
Повний текст джерелаPezzi, Luciano Ponzi. "Equatorial Pacific dynamics : lateral mixing and tropical instability waves." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274585.
Повний текст джерелаBlumenthal, Martin Benno. "Interpretation of equatorial current meter data as internal waves." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/51460.
Повний текст джерелаBibliography: v. 2, leaves 376-381.
by Martin Benno Blumenthal.
Ph.D.
Yu, Xuri. "Dynamics of seasonal and interannual variability in the equatorial Pacific." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11065.
Повний текст джерелаDrysdale, Euain Fraser. "Modelling of equatorial wave motions in the middle atmosphere." Thesis, University of Oxford, 1998. http://ora.ox.ac.uk/objects/uuid:9ae75869-a15b-465e-af64-c608cca8b34c.
Повний текст джерелаSoares, Jacyra Ramos. "On the reflection of the equatorial waves at eastern ocean boundaries." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239653.
Повний текст джерелаAndersen, Joseph. "Investigations of the Convectively Coupled Equatorial Waves and the Madden-Julian Oscillation." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10438.
Повний текст джерелаPhysics
Aveiro, Henrique Carlotto. "Electric and magnetic field signatures of gravity waves and 2-day planetary waves in the equatorial E-region." Instituto Nacional de Pesquisas Espaciais, 2009. http://urlib.net/sid.inpe.br/mtc-m18@80/2008/12.16.11.31.
Повний текст джерелаEquatorial electrojet (EEJ) observations using VHF radars show backscattered echoes from two types of electron density irregularities explained by the modified two-stream (Type I) and the gradient drift (Type 11) instabilities. From the Type II irregularity velocities obtained by radar data we have inferred the vertical electric fields (E_z). The harmonic analysis of such fields shows the presence of gravity waves-induced electric fields in the EEJ. We calculated the ratio between GW-related electric fields and the total E_z. This factor is an indicator of the efficiency in the production of an additional electric field due to a gravity wave neutral wind. Also, we analyze the effects of the 2-day wave activity in the EEJ using one coherent radar and eight magnetometer stations located dose to the dip equator. The wavelet analysis of the magnetometer data reveals a 2-day signature in the semidiurnal geomagnetic tide. The E-region zonal background ionospheric electric field derived from coherent radar measurements shows 2-day oscillations in agreement with such oscillations in the magnetometer data set. An anticorrelation between the tidal periodicites (diurnal, and semidiurnal) and the 2-day signature is also shown in the electric fields. The results are compared with simultaneous observations of 2-day planetary wave in meridional winds and ionosondes available in the literature. Our results are discussed based on the analysis of the magnetic activity.
Norton, Andrew David. "Analysis of Ionospheric Data Sets to Identify Periodic Signatures Matching Atmospheric Planetary Waves." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101791.
Повний текст джерелаMaster of Science
The thermosphere and ionosphere are impacted by many sources. The sun and the magnetosphere externally impact this system. Planetary waves, which originate in the lower atmosphere, internally impact this system. This interaction leads to periodic signatures in the ionosphere that reflect periodic signatures seen in the lower atmosphere, the sun and the magnetosphere. This study identifies these times of similar oscillations in the neutral atmosphere, the ionosphere, and the sun, in order to characterize these interactions. Events are cataloged through wavelet analysis and thresholding techniques. Using a time-span of 17 years, trends are identified using histograms and percentages. From these trends, the characteristics of this coupling can be concluded. This study is meant to confirm the theory and provide new insights that will hopefully lead to further investigation through modeling. The goal of this study is to gain a better understanding of the role that planetary waves have on the interaction of the atmosphere and the ionosphere.
Sitler, Todd William. "An observational study of long waves in the equatorial Pacific Ocean during the 1991-1993 El Nino." Thesis, Monterey, California. Naval Postgraduate School, 1994. http://hdl.handle.net/10945/28415.
Повний текст джерелаLong waves in the equatorial Pacific Ocean during the 1991-1993 El Nino event were examined using temperature, current, and wind time series from the Tropical Oceans-Global Atmosphere Tropical Atmosphere-Ocean (TOGA-TAO) moored buoy array. Numerous episodes of long wave activity were detected. The most prominent episodes were associated with eastward propagating equatorial Kelvin waves and with westward propagating tropical instability waves and mixed Rossby-gravity waves. Equatorial Kelvin waves, which were generated by westerly wind events in the western and central Pacific, were evident in the data between 2 deg N to 5 deg S and from 170 deg W to 110 deg W. These Kelvin waves, which were most pronounced from 75 to 300 m, had periods of 40 to 70 days, eastward phase speeds of 1.9 to 6.5 m/s, and zonal wavelengths on the order of 10,000 km. These waves were most evident in the northern hemisphere fall and winter. The period of greatest Kelvin wave activity was August 1991 -May 1992, during the peak phase of the 1991-1993 El Nino event
Ponte, Rui Vasques de Melo. "Observations and modelling of deep equatorial currents in the central Pacific." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/58499.
Повний текст джерелаIncludes bibliographical references (leaves 178-180).
Analysis of vertical profiles of absolute horizontal velocity collected in January 1981, February 1982 and April 1982 in the central equatorial Pacific as part of the Pacific Equatorial Ocean Dynamics (PEQUOD) program, revealed two significant narrow band spectral peaks in the zonal velocity records, centered at vertical wavelengths of 560 and 350 stretched meters (sm). Both signals were present in all three cruises, but the 350 sm peak showed a more steady character in amplitude and a higher signal-to-noise ratio. In addition, its vertical scales corresponded to the scales of the conspicuous alternating flows generically called the equatorial deep jets in the past (the same terminology will be used here). Meridional velocity and vertical displacement spectra did not show any such energetic features. Energy in the 560 sm band roughly doubled between January 1981 and April 1982. Time lagged coherence results suggested upward phase propagation at time scales of about 4 years. East-west phase lines computed from zonally lagged coherences, tilted downward towards the west, implying westward phase propagation. Estimates of zonal wavelength (on the order of 10000 km) and period based on these coherence calculations, and the observed energy meridional structure at this vertical wavenumber band, seem consistent, within experimental errors, with the presence of a first meridional mode long Rossby wave packet, weakly modulated in the zonal direction. The equatorial deep jets, identified with the peak centered at 350 sm, are best defined as a finite narrow band process in vertical wavenumber (311-400 sm), accounting for only 20% of the total variance present in the broad band energetic background. At the jets wavenumber band, latitudinal energy scaling compared well with Kelvin wave theoretical values and a general tilt of phase lines downward towards the east yielded estimates of 10000-16000 km for the zonal wavelengths.
by Rui Vasques de Melo Ponte.
Ph.D.
Horinouti, Takeshi. "Excitation of waves by organized cumulus convection and their interaction with the mean flow in the equatorial middle atmosphere." 京都大学 (Kyoto University), 1997. http://hdl.handle.net/2433/202444.
Повний текст джерелаJacobi, Christoph. "The quasi 16-day wave in the summer midlatitude mesopause region and its dependence on the equatorial quasi-biennial oscillation." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-213442.
Повний текст джерелаFrom daily estimates of the summer mesopause region zonal prevailing wind measured at the Collm Observatory of the University of Leipzig long-term variations in the period range of planetary waves (10-20 days) are detected. Although the direct propagation of these waves from lower layers into the mesosphere is not possible because of the wave filtering in the summer stratospheric and mesospheric easterlies, in some years oscillations are found that can be connected with planetary waves, supporting the theory of the propagation of these waves from the equatorial region to the midlatitude and polar upper mesosphere along the zero wind line. The interannual variability of these waves shows a dependence on the equatorial quasi-biennial oscillation (QBO), so that in general during the east phase of the QBO the planetary wave activity is small, while during the QBO west phase it can be larger. The influence of the QBO on the planetary wave activity is modulated by the I I-year solar cycle, so that the strongest signal is found during solar maximum
Lima, Newton Silva de. "Estudo da propagação de ondas de gravidade na ionosfera equatorial, utilizando observações em Manaus (2,9°s, 60°w)." Universidade Federal do Amazonas, 2009. http://tede.ufam.edu.br/handle/tede/3275.
Повний текст джерелаCAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This work studies the behavior of gravity waves (GW) in the ionosphere over the city of Manaus (2,9oS, 60oW). For that purpose, ionograms which are specters of frequency in function of the altitude and the secular variation of the height for a set of fixed frequencies (3, 4, 5, 6, 7 8 MHz). The observations were analyzed carried through by a system of called radar ionosonde. This system operates in the radio frequency band between 1and 20 MHz. The studied period comprehends a part of solar cycle 23, that is, since August of 2002 until December of 2006. Additionally, it was also observed that the ionosphere presents strong disturbances during geomagnetically quiet periods. These disturbances are attributed to the propagation of gravity waves which are generated in the lower atmosphere and propagate up to the high atmosphere and ionosphere.
Este trabalho investiga o comportamento de ondas de gravidade (OG) na ionosfera sobre a cidade de Manaus (2,9oS, 60oW). Para tal, foram analisados ionogramas que são espectros de freqüência em função da altitude e a variação temporal da altura, para um conjunto de freqüências fixas (3, 4, 5, 6, 7 8 MHz). As observações foram realizadas por um sistema de radar chamado ionossonda; que pera na faixa de rádio freqüência entre 1 e 20 MHz. O período estudado compreende uma parte do ciclo solar 23, ou seja, desde agosto de 2002 até dezembro de 2006. Observou-se que a ionosfera apresenta fortes perturbações durante períodos geomagneticamente calmos. Estas perturbações são atribuídas a propagação de ondas de gravidade que são geradas na baixa atmosfera e se propagam até a alta atmosfera e ionosfera.
Moss, Andrew. "Wave dynamics of the stratosphere and mesosphere." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707571.
Повний текст джерелаJacobi, Christoph. "The quasi 16-day wave in the summer midlatitude mesopause region and its dependence on the equatorial quasi-biennial oscillation." Wissenschaftliche Mitteilungen des Leipziger Instituts für Meteorologie ; 9 = Meteorologische Arbeiten aus Leipzig ; 3 (1998), S. 117-129, 1998. https://ul.qucosa.de/id/qucosa%3A15084.
Повний текст джерелаFrom daily estimates of the summer mesopause region zonal prevailing wind measured at the Collm Observatory of the University of Leipzig long-term variations in the period range of planetary waves (10-20 days) are detected. Although the direct propagation of these waves from lower layers into the mesosphere is not possible because of the wave filtering in the summer stratospheric and mesospheric easterlies, in some years oscillations are found that can be connected with planetary waves, supporting the theory of the propagation of these waves from the equatorial region to the midlatitude and polar upper mesosphere along the zero wind line. The interannual variability of these waves shows a dependence on the equatorial quasi-biennial oscillation (QBO), so that in general during the east phase of the QBO the planetary wave activity is small, while during the QBO west phase it can be larger. The influence of the QBO on the planetary wave activity is modulated by the I I-year solar cycle, so that the strongest signal is found during solar maximum.
Costa, Carine de Godoi Rezende. "Dinâmica e interação oceano-atmosfera de ondas de instabilidade tropical e ondas de Rossby curtas." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/21/21135/tde-10042014-165427/.
Повний текст джерелаWe hypothesize that rainfall anomalies with 2050 days and 10001500 km on the Intertropical Convergence Zone (ITCZ) can induce sea surface salinity anomalies. We argue that these precipitation anomalies are remotely caused by Tropical Instability Waves (TIWs) and Short RossbyWaves (SRWs). We have quantified the sea surface temperature influence on atmospheric fields at the TIWs and SRWs spectral bands through regression analysis. In that, wind anomalies are larger over temperature anomalies. Winds tend to accelerate over positive temperature anomalies and slow down over negative anomalies. Changes on water vapor and rainfall occur predominantly on the ITCZ, far from the strongest temperature anomalies near the equator. However, we couldnt address the main hypothesis due to the lack of significant correlation between rainfall and sea surface salinity anomalies. We speculate that this is a consequence of the low quality of the salinity data used in this study. We have identified TIWs as the waves with _21 days and _1000 km and SRWs as the oscillations with _49 days and _1500 km. The identification of the dynamics was made according to equatorial long waves theory based on a linear, quasi-geostrophic, 1.5 layers, inviscid ocean model. Sea surface height anomalies could only reveal SRWs. Sea surface temperature anomalies show both type of waves, with TIWs dominating within 6_ from the equator. Our main contribution was to show that TIWs and SRWs coexist, can be isolated and change wind field through similar mechanisms. We do not know any other study that linked theoretical identification of dynamically different oceanic waves to the atmospheric variability in a quantitative fashion
Phlips, P. J. "Models of the heat-induced circulation in the tropical atmosphere." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371572.
Повний текст джерелаWohlwend, Christian Stephen. "Modeling the Electrodynamics of the Low-Latitude Ionosphere." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/11.
Повний текст джерелаBrady, Esther C. "Observations of wave-mean flow interaction in the Pacific equatorial undercurrent." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/51482.
Повний текст джерелаGRSN 539404
Includes bibliographical references (p. 207-216).
by Esther Collison Brady.
Ph.D.
Mosquera, Vasquez Kobi A. "L'onde de Kelvin équatoriale océanique intrasaisonnière et les événements El Nino du Pacifique central." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30324/document.
Повний текст джерелаThe El Niño phenomenon is the dominant mode of climate variability at interannual timescales in the tropical Pacific. It modifies drastically the regional climate in surrounding countries, including Peru for which the socio-economical impacts can be dramatic. Understanding and predicting El Niño remains a top-priority issue for the climatic community. Large progress in our understanding of El Niño and in our ability to predict it has been made since the 80s thanks to the improvement of the observing system of the tropical Pacific (TOGA program and emergence of the satellite era). At the end of the Twentieth century, whereas new theories were proposed and tested, progress in numerical modeling and data assimilation led to the idea that El Niño could be predicted with at least 2 or 3 seasons in advance. The observations since the beginning of the 21st century have wiped out such expectation: A new type of El Niño, known as the Central Pacific El Niño (CP El Niño) or Modoki El Niño has put the community in front of a new challenge. This thesis is a contribution to the current international effort to understand the dynamics of this new type of El Niño in order to propose mechanisms explaining its increased occurrence in recent decades. More specifically, the objective of the thesis is to study the role of the oceanic equatorial waves in the dynamic and thermodynamic along the equatorial Pacific Ocean, focusing on the CP El Niño. This thesis first takes a close look at the first CP El Niño of the 21st century of this type, i.e. the 2002/03 El Niño, based on an Oceanic General Circulation Model. Then it documents the characteristics of the IntraSeasonal Kelvin waves (ISKws) over the period 1990-2011, providing a statistics on the ISKws activity during the evolution of CP El Niño events. We find that the ISKw experiences a sharp dissipation in the eastern Pacific that is interpreted as resulting from the scattering of energy associated to the zonal contrast in stratification (i.e. sloping thermocline from west to east). Partial reflection of the ISKw as Rossby waves near 120°W is also identified, which may explain the confinement of CP El Niño warming in the central Pacific. We suggest that the increased occurrence of CP El Niño in recent years may be associated to the La Niña-like state since the 90s and changes in the seasonality of the thermocline since the 2000s
Awo, Founi Mesmin. "Modes interannnuels de la variabilité climatique de l'Atlantique tropical, dynamiques oscillatoires et signatures en salinité de surface de la mer." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30171/document.
Повний текст джерелаIn this thesis, we investigate several topics related to the interannual climatic modes in the tropical Atlantic. Statistical analyses allows us to extract the two main dominant modes of interannual variability: an equatorial mode and a meridional mode. The equatorial mode is responsible for Sea Surface Temperature (SST) anomalies mainly found in the Gulf of Guinea and is linked to variations of the sea-level slope in the equatorial band. It is due to dynamic feedbacks between zonal wind, sea level and SST. The meridional mode is characterised by inter-hemispheric SST fluctuations and is controlled by dynamic and thermodynamic feedbacks between the wind, evaporation and SST. After quantifying the coupling between key variables involved in the meridional mode, we develop a conceptual model to explain the main mechanisms responsible for meridional mode oscillations. The model shows that the meridional mode results from the superposition of a self-sustaining mechanism based on positive and negative feedbacks generating regular oscillations of high frequency (2-3 years) and another low frequency oscillation mechanism (4-9 years) related to the influence of ENSO. As the evolution of these two modes is strongly linked to the meridional shift of the Intertropical Convergence Zone (ITCZ) and associated rainfall maximum, we identify the signature of these modes on Sea Surface Salinity (SSS) using in situ observations and a regional numerical simulation. Oceanic and/or atmospheric processes responsible for the signature of each mode are also identified through a mixed-layer salt budget in the validated model. The salt balance reveals that the atmospheric forcing, related to the ITCZ migration, controls the equatorial region while the advection, due to the modulation of current dynamics, the vertical gradient and mixing at the base of the mixed layer, explains SSS variations in regions under the influence of plumes. Finally, we study the Equatorial Kelvin wave characteristics and influences on the density that are involved in the meridional and equatorial mode connection processes, using a very simplified model of gravity wave propagation along the equator. After a brief description of this model, which was initially constructed to study dynamics in the equatorial Pacific, we apply it to the specific case of the equatorial Atlantic by validating its analytical and numerical solutions under adiabatic conditions. [...]
Donohue, Kathleen A. "Wave propagation in the central equatorial Pacific Ocean." 1995. http://catalog.hathitrust.org/api/volumes/oclc/35904424.html.
Повний текст джерелаMack, Andrew P. "High-frequency internal waves in the upper eastern equatorial Pacific." 1997. http://catalog.hathitrust.org/api/volumes/oclc/41182637.html.
Повний текст джерелаTsai, Yu-Ying, and 蔡玉嫈. "Equatorial waves observed using FORMOSAT-3 GPS Occultation." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/8d2n48.
Повний текст джерела國立中央大學
太空科學研究所
96
Structure and propagation of equatorial atmospheric Kelvin waves and the latitudinal migration of intertropical convergence zone (ITCZ) during August 2006 and February 2008 are observed using FORMOSAT-3/COSMIC data. Zonal Kelvin wave derived from temperature fluctuations at 19 km characterize eastward phase propagation with the phase speed 2680 km/day, the wave periods are 12-17 days for zonal wave number 1 and 8-12 days for wave number 2. The vertical structure of Kelvin wave tilts eastward with height between 18-30 km, the phase propagates downward with the phase speed 0.5-1 km/day, and vertical wavelengths are 4-6 km in 2006 and 6-10 km in 2007. Integrated water vapor derived from COSMIC data shows one year variation in time-latitude section, high value region moved to the most southern part and northern part on February and August. It shows the characteristics of the latitudinal migration of ITCZ.
Sun, Chaojiao. "Dynamic instability of stratified shear flow in the upper equatorial Pacific." Thesis, 1997. http://catalog.hathitrust.org/api/volumes/oclc/39803516.html.
Повний текст джерелаGall, Jeffrey S. Frank William M. "The role of equatorial Rossby waves in tropical cyclogenesis /." 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-3735/index.html.
Повний текст джерелаSeidel, Howard Franklin. "Impact of realistic mean flow on equatorial waves in the Pacific Ocean." 1999. http://catalog.hathitrust.org/api/volumes/oclc/43964645.html.
Повний текст джерелаFern, C. L., and 馮志龍. "Simulations of Pure Two-Stream Waves in the Equatorial E-region Ionosphere." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/74234128445303163268.
Повний текст джерела國立中央大學
太空科學研究所
89
At the altitude range of 95∼110 km in the equatorial E-region ionosphere, a large current in the magnetic equator called the equatorial electrojet is created by a dynamic process involving atmospheric tides. The equatorial electrojet causes the medium to be unstable to generate plasma waves. Radar observations have shown the existence of two classes of plasma waves, called typeⅠand typeⅡ. The typeⅠwave resulting from the two-stream instability is also called two-stream wave. In this paper, the behavior of two-stream wave in the plane perpendicular to the Earth's magnetic field is simulated by a two-dimensional fluid model simulation code in which the electron inertia is neglected while the ion inertia is retained. We consider the suitable two-dimensional simulation space (27×54m ) and successfully excite the dominant 3-meter wave compatible with VHF radar echoes. The analysis methods of two-dimensional Fourier series are derived to express the time variation of mode powers and ω spectra. From the series of simulation results for two-stream waves in the equatorial E-region ionosphere, we have studied the dispersion relations, the resonant coupling, and the echo power variation with the zenith angle rate of approximately 0.3(dB/degree). We have also studied the vertical small-scale waves developed from the distortions of the dominant waves. The vertical waves will cause dominant waves to turn away from the electrojet drift direction (E×B ). The important point about the development of vertical modes is asymmetry. We find that the spectral asymmetry depends on the scale size of plasma waves, that is, the large-scale waves (above 3 meters) propagate in the k‧E<0 region, and the small-scale (smaller than 3 meters) propagate in the k‧E>0 region. The simulation result of up-down asymmetry for 3-meter wave is consistent with the radar observations. We believe that the background polarization electric field E driving the electrojet is responsible for the spectral asymmetries. In the same time, owning to the strong and fixed background polarization electric field E , the wave frequency depends only on horizontal wave number Kx . Therefore, the phase velocities of many obliquely propagating two-stream waves (Kz≠0 ) are below the value predicted by linear theory, and this characteristic is prominent especially for large-scale waves.
Ascani, Francois. "Wave-induced deep equatorial ocean circulation." Thesis, 2008. http://hdl.handle.net/10125/20786.
Повний текст джерелаFor weak Yanai wave amplitude, currents resembling the TEJs are obtained, but only within the beam. They are the mean Eulerian flow, which cancels the Stokes drift of the Yanai waves, yielding a zero-mean Lagrangian flow: the water parcels conserve their potential vorticity (PV) and are stationary over a wave cycle. With stronger amplitude, the Yanai waves become unstable, and lose their energy to small vertical scales where it is dissipated. The resulting vertical decay of the Yanai waves provides a source of PV, allowing water parcels to move meridionally within the beam. This process results in TEJs with a mean Lagrangian zonal flow extending to the west of the beam.
In the Pacific and Atlantic oceans, a complex equatorial current structure is found below the thermocline. The currents are zonal with typical speeds from 5 to 20 cm s-1 and extend as deep as 2500 m. The structure can be divided into two overlapping parts: the Tall Equatorial Jets (TEJs), with large vertical scale and alternating with latitude, and the Equatorial Deep Jets (EDJs), centered on the equator and alternating in the vertical with a wavelength of several hundred meters.
In the present study, using idealized numerical simulations and analytical solutions, we demonstrate that the TEJs could result from a rectification of a beam of monthly-periodic Yanai waves that is generated in the eastern part of the basin by instabilities of the swift equatorial surface currents.
This circulation poses a computational and a theoretical challenge. First, state-of-the-art high-resolution regional models and Ocean General Circulation Models (OGCMs) typically produce a rather weak, inaccurate and incomplete picture of the circulation. Second, the most promising existing theory, based on the rectification of intraseasonal Yanai waves, cannot account for the basin-wide presence of the TEJs.
Includes bibliographical references (leaves 148-157).
Also available by subscription via World Wide Web
158 leaves, bound 29 cm
Das, Surajit. "Role Of Sea Surface Temperature Gradient In Intraseasonal Oscillation Of Convection In An Aquaplanet Model." Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2583.
Повний текст джерелаHyungeun, Shin. "Effect of equatorially trapped waves on the tropical cyclone drift." Thesis, 2019. http://hdl.handle.net/1828/11211.
Повний текст джерелаGraduate
Namazi, Maryam. "Interaction of equatorially trapped waves and a background shear: numerical and theoretical issues." Thesis, 2010. http://hdl.handle.net/1828/3198.
Повний текст джерелаHsu, Shih-Pei, and 徐世裴. "Characteristics of Equatorial Rossby Wave in western North Pacific during Warm Season." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/25562130257435013084.
Повний текст джерела國立臺灣大學
大氣科學研究所
103
Equatorial Rossby wave (ER) is most active in western North Pacific (WNP) than in other tropical regions. Its active season starts from mid-May to mid-November when warm SST, cyclonic vorticity, zonal wind convergence and easterly vertical wind shear provide a preferable environment for ER to amplify in WNP. We perform an analysis of space-time filtered ER based on 10 years of data to extract ER signals. Two dominant types of ER are identified through an EOF analysis on 850mb ER vorticity and a subjective inspection of strong ER cases related to tropical disturbances. The 850mb horizontal structure of type-I ER features a wave structure along 7.5°N and 17.5°N. The ER vorticity and divergence are out of phase between the two latitudes within the wave train. The amplitude of the northern center is larger than that of the southern center. Stronger convection appears in the northern side exhibiting a first baroclinic structure. The southern side is associated with weaker convection and an equivalent barotropic vertical structure. The 850mb horizontal structure of type-II ER shows a dominant southwest-northeast tilted wave pattern indicating an unstable ER. For both types of ER, the positive (negative) phase of vorticity is accompanied with convergence (divergence) and convection (suppressed convection). The variance of vorticity for the two types of ER shows that they are most active within 90°E to 160°E and 5°N to 25°N. Type-II ER has a larger amplitude than that of type-I ER. Type-II ER is associated with stronger LF westerly wind anomaly (relative to summer climatology) than type-I ER; therefore LF zonal wind convergence is stronger and located more eastward for type-II ER. ER kinetic energy (KE) budget of multi-scale interaction is used to discuss the relationship between the two types of ER and their low frequency background state (LF). To derive ER KE budget equation, all variables are decomposed into three bands: LF, ER and high frequency field (HF). The contribution to the tendency of ER in the ER band (KT) is separated into generation from LF-ER interaction (KTEL) and HF-related interaction (KTH). KT gains via KTEL and loses through KTH. Two predominant processes contributing to KTEL are barotropic energy conversion (BC) and eddy geopotential flux convergence (GF). BC is mainly contributed by an accumulation of ER kinetic energy through low-frequency zonal wind convergence. Thus ER-II amplifies in a broader zonal extent east of that of ER-I. In addition, the ER momentum flux uv in northeast-southwest tilted type-II ER waves converts low-frequency kinetic energy with zonal wind shear into ER kinetic energy.. GF has positive contribution to KTEL in lower troposphere
Liu, Yurun. "Nontraditional approximation in geophysical fluid dynamics." Thesis, 2009. http://hdl.handle.net/2152/ETD-UT-2009-05-156.
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Ferguson, James. "A numerical solution for the barotropic vorticity equation forced by an equatorially trapped wave." Thesis, 2008. http://hdl.handle.net/1828/1218.
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